Fluid pressure braking system



Dec. 17, 1935. w AT 2,024,343

FLUID PRESSURE BRAKING SYSTEM Filed Aug. 18, 1932 s Sheets-Sheet 1 Dec.1 7, 1935. w, EATON 2,024,343

FLUID PRESSURE BRAKING SYSTEM Filed Aug. 18, 1932 6 Sheets-Sheet Dec.17, 1935. w. A. EATON 2,024,343

FLUID PRESSURE BRAKING SYSTEM Filed Aug. 18, 1952 6 Sheets-Sheet 3 Dec,17, 1935. w, A, EATON 2,024,343

FLUID PRESSURE BRAKING SYSTEM Filed Aug. 18, 1952 6 Sheets-Sheet 4 Dec.17, 1935. v w, A, EATON 2,024,343

FLUID PRESSURE BRAKING SYSTEM Filed Aug. 18, 1932 6 Sheets-Sheet 5 Dean,1935. w. A. EATON 2,024,343

FLUID PRESSURE BRAKING SYSTEM Filed Aug. 18, 1932 6 Sheets-Sheet Q 7'0TRACTOR RELAY VALVE EXHAUST TEA! LER Wfl. Edison,

Patented Dec. 17, 1935 2,024,343

4 Claims. (Cl. 303-26) UNITED STAT This invention relates to brakes andmore particularly to fluid pressure braking systems for tractor-traflervehicles.

It is an object of the present invention to profluid pressure brakingsystem according to the present invention,

Fig. 3 is a view showing another modified system,

vide a fluid pressure braking system for tractor- Fig. 4 is a viewshowing still another modifica- 5 trailer vehicles which will be sodesigned that in tion of the present invention, the event of any failureof the 'air lines between Fig. 5 is a view showing a furthermodification, the two vehicles, no adverse effect on the brak- Fig. 6 isa sectional view showing the trailer ing system of either vehiclewill-result. relay-emergency valve disclosed more generally 10 Anotherobject of the invention is to provide a, in other figures of thedrawings, and 10 fluid pressure braking system for tractor-trailer Fig.'7 is a sectional view showing the relay vehicles which will includemeans for' insuring valve construction disclosed more generally intractor brake operation upon failureof the air other figures. j linesbetween thetwo vehicles. a Referring particularly ,to Fig. 1 of thedraw- Another object is to provide a fluid pressure ings, wherein isdisclosed what may be considered 15 braking system which will includenovel means the preferred embodiment of the system, it will' forautomatically operating the brakes of the be seen that such systemincludes a compressor trailer vehicle in the event of that vehiclebreak- I. supplying fluid under pressure, such as coming away from thetractor vehicle. pressed air, to reservoirs 2 and 3 through pipes Afurther object is to provide a braking system "4 and 5, thesame'including check valves 0 and I 20 for a four wheeled vehicle inwhich thefailure of which allow compressed fluid to flow from the eitherthe front or rear brake line will'not precompressor to the reservoirsbut not in the oppovent operation of the other set of brakes. sitedirection. A brake valve 8 is provided, the A still further object is toprovide a tractorlower chamber of the same. being connected to trailerbraking system in which means are proreservoirs 2 and 3 by pipe 9 andconnecting pipes 2 vided for sealing off either the brake system on l0and II, the same including check valves I2 the tractor or that on thetrailer on breaking of and I3, which allow flow of fluid under pressurethe other system or pulling apart of the two from the reservoirs to thebrake valve but not vehicles; in the opposite direction. :20 A stillfurther object isto provide a tractor- Relay valves l4 and ii areprovided on the trailer fluid-pressure braking system including tractor,and the upper chambers 20l thereof, novel means operating in series fortransmitting Fig. '7, are connected to brake valve 8 by pipes fluidunder pressure and for sealing off any porl0 and I1, wherebysaid'chambers may be contion of the system which has failed. nected toreservoirs 2 and 3 on operation of brake A still further object is toprovide a-fluid presvalve 8. Chamber 202 of relay valve .is con- 35 surebraking system including a plurality of nectedby pipes l8 and I0respectively to front sources of fluid under pressure operating inconbrake chambers 20 and rear brake chambers 2L junction with relaymeans for transmitting fluid Chamber 203 of relay valve I4 is connectedby under pressure and insuring operation of a part pipes 22 and 23 toreservoir 2, pipe 22 also lead- ,40 of the braking system on failure ofany other ing to a governor unit 24 which is connected to 40 part of thesystem. compressor I through pipe 25 for controlling the Other objectsand novel features of the invenoperation of the same. Chamber 203 ofrelay tion will appear from the following detailed devalve i5 isconnected by pipes 20 and 21 to reserscription when taken in connectionwith the voir 3, pipe 20 being also connected to a-pipe 20 accompanyingdrawings. It is expressly underwhich connects to the trailer emergencyline 45 ,stood, however, that the drawings are for pur- 3|. Chamber 202of relay valve I5 is connected poses of illustration only and are not tobe taken to a pipe 29 which connects to the trailer service as adefinition of the limits of the invention, line 30. reference being hadfor this purpose to the ap-.- The trailer equipment comprises arelay-emerpended claims. 7 gency valve, the same being more fullyillustrated 50 In the drawings, in which similar reference in Fig. 6 ofthe drawings. Chamber 250 of such numbers refer to similar parts: valveis connected to trailer service line 30, and Fig. 1 is a view showing afluid pressure br'akchamber 25! of the emergency portion of such ingsystem according to'the-present invention, valve is connected to thetrailer emergency line Fig. 2 is a view showing a modified form of the3| Trailer reservoir 33 is connected by pipe 34 55 reservoir 3 2 tochamber 252 of the relay-emergency valve, and trailer brake chambers 35are connected by piping 38 to chamber 253 01' this valve. As shown,chambers 25| and 252 are separated by a diaphragm 258 the periphery ofwhich is normally seated upon a portion of the valve casing while thecentral portion thereof normally contacts a ridge or seat 259. Anormally open valve 251, interposed betweenchambers 253 and 256 iscarried by the central portion of the diaphragm 258, the stem of saidvalve carrying a guide member 251' in the form of a disk, having asegment thereof cut'away to form a small opening 25 1 between chambers252 and 253 when these latter are placed in communication as will appearmore fully hereinafter. I It is to be understood that the specificconstruction of the relay-emergency valve, as well as that of the relayvalves, forms no part of the present invention.

In operation of the system disclosed in Fig. l, the compressor Isupplies fluid under pressure to reservoirs 2 and 3, this fluid beingsupplied at all times to valve 8. On operation of valve 8, fluid underpressure will flow from the said valve to chambers 20| of relay valvesl4 and I5, operat ing the diaphragm 204 in each of such valves, closingthe exhaust ports 205,-and connecting chambers 202 and 203. Suchoperation of relay valve |4 efl'ects the connection of tractor frontbrake chambers 20 to reservoir 2 through pipe l8, chambers 202 and 203of relay valve l4, and pipes 22 and 23, and also the connection of tra'ctor rear brake chambers 2| to reservoir 2 through pipe l9, chambers 202and 203 of relay valve l4, and. pipes 22 and 23, thereby applying alltractor brakes. Operation of relay valve l5, as outlined above, causesfluid pressure from reservoir 3 to flow. through pipes 26 and 21,chambers 203 and 202 of relay valve l5, and pipes 29 and 30 to chamber250 of trailer relay-emergency valve 32, operating the diaphragm 254 andvalve 255 therein, andconnecting trailer reservoir 33 to trailer brakechambers 35 through pipe 34, chamber 252, past valve 255, chamber 256,past opened valve 251, to chamber 253, and through pipe 36 to the brakechambers.- It will be seen that valve 251 is held in open position bypressure from tractor acting in chamber 25| against the lower side ofdiaphragm 258.

In the event of failure of any of lines I8, 22, 23, I0 or I9, reservoir2 will drain to the atmosphere on operation of brake .valve 8 to eilecta normal service application. Due, however, to the interposition ofcheck valves 6 and I2, reservoir 3 will not drain and pressure from thisreservoir will be available to operate relay valve l5 and thereby causean application of the trailer brakes. No application of any tractorbrakes may be had, however, in the event of the failure of any of theabove-noted lines.

In case of failure of either of lines l6 or l1, both tractor reservoirswill drain to the atmosphere upon application of the brake valve 8 and.the consequent reduction in. pressure in reservoir 3 and pipes 28 and 3|will cause an emergency operation of "trailer relay-emergency valve 32,'thereby connecting trailer reservoir 33 to the trailer brake chambersand applying the trailer brakes.

Assuming failure of any of lines 9, 26, 21, 28 or 3| reservoir 3 willimmediately drain to the atmosphere, thereby reducing the pressure inchamber 25| of trailer relay-emergency valve 32 and eflecting anemergency operation of such valve, thereby connecting trailer reservoir33 to check valve trailer brake chambers It will be noted that suchoperation is entirely automatic and is not dependent upon operation ofthe tractor brake valve.

2 of the drawings it will be observed that compressor 50 is connected bypipe 5| to reservoir 52, .said reservoir being connected to a secondreservoir 53 by a pipe 54 including a one-way check valve 55. Reservoir53' is connected by a pipe 56 to the usual brake valve 51, and suchbrake valve is in turn connected to tractor front brakechambers 58 bypipes 59 and 60, and to tractor rear brake chambers 6| by pipes 62 and63, whereby upon operation of the brake valve, fluid under pressure fromreservoirs 52 and 53 may be transmitted to brake chambers 58 and 6| toeifect a braking of the vehicle. A relay valve 64, Fig. 7, is provided,and the chamber 20| thereof is connected by pipe to the pipe 63 20leading to the brake valve whereby on brake-applying operation of thelatter, fluid under pressure will be transmitted to chamber 20| of therelay valve. Chamber 203 of the relay valve is connected by pipes 66 and61 to reservoir 52, and 2! I chamber 202 of the said valve is connectedby pipe 68 to the trailer service pipe 69 which nects to chamber 250 ofthe trailer relay-emergency valve 1|, the same being more fullydisclosed in Fig. 6 of the drawings.

is constantly connected by pipe 10 to trailer emergency line 12 which isconnected to chamber 25| of the trailer relay-emergency valve 1| wherebyfluid under pressure from reservoir 53 acts on diaphragm 258 tomaintainvalve 251 in opened 5 position. A trailer reservoir 13 is provided andis connected by pipe 14 to chamber 252 of' the trailer relay-emergencyvalve 1|. Trailer brake chambers 15 are connectedby piping 16 and 11 tochamber 253 of the relay-emergency valve.

A governor unit 18 is provided for compressor 50 and is connectedthereto by pipin'g 19 and to reservoir 52 by piping 80.

In operation of the above-described system, compressor 50 supplies fluidunder pressure, such 45 as compressed air, to reservoirs 52 and 53, the

permitting flow from the compressor 50 and reservoir 52' to reservoir53, but not in the opposite direction. Fluid under pres,- sure from thereservoirs is constantly fed to 50 brake valve 51 and, an operation ofsuch valve, fluid under pressure is supplied to the tractor front brakechambers 58 through pipes 59 and 60, to the tractor rear brake chambersthrough pipes 63 and 62, and to chamber 20| of relay 55 valve 64 throughpipes 63 and 65, thereby actuating'all the tractor brakes. Fluid underpressure in chamber 20| of relay valve 64 ,will act to depress diaphragm204, close the exhaust port 205, and connect fluid under pressure willflow from reservoir 52 through pipes 61 and 66, chambers 203' and 202 ofrelay valve 64, pipe 68 and trailer service pipe 69, to chamber 250 ofthe relay-emergency valve 250. Fluid under pressure in chamber 250 ofthe 65 relay-emergency valve will act to depress dia-' phragm 254 andopen valve 255, thereby connecting trailer reservoir 13 to trailer brakechambers 15 through pipe 14, chamber 252 of the relayemergency valve,256, piping 11 and 16, brakes. I

In the event of failure of any of the pipes 59, j 60, 62, 68 or 65, bothtractor reservoirs will drain" past opened valve .251, chamber 253', and

Referring now to the system illustrated in Fig. 5

COII- Reservoir 52 30 chambers 202 and 203, whereby past opened valve255, chamber 70 thereby applying the trailer to atmosphere through thebroken line on service operation of the brake valve. The consequent Incase-of failure of any of pipes 5|, 80, 66, 51,

I0, I2 or that part of pipe 54 between reservoir 52 and check valve 55,the reservoir 52 will immediately drain to the atmosphere and theconsequent reduction-of pressure in chamber 25I of the trailerrelay-emergency valve will cause an emergency operation of such valve.thereby applying the trailer brakes immediately. It will be noted thatsuch operation is immediate and automatic, and is not dependent uponoperation of the brake valve 51. It is also'to be noted that on failureof any of the lines referred to, reservoir 53 will not drain toatmosphere through reservoir 52 due to the interposition and dispositionof check valve 55, and due to the direct connections between the tractorbrake chambers and the brake valve, a normal service operation of thebrake valve will result in operation of the tractor brakes, regardlessof the broken lines referred to.

Assuming failure of line 55 or that portion of line 54 between reservoir53 and check valve 55,

both tractor reservoirs will drain to atmosphere, no power braking onthe tractor will be possible, and the reduction of pressure in reservoir52, and consequently in chamber 25I of trailer relayemergency valve II,will cause an emergency application of the trailer brakes.

In the event of failure-of either of lines 68 or I59, reservoir 52 willdrain to atmosphere on service operation of the brake valve, and theconsequent reduction in pressure in chamber 25I of the trailerrelay-emergency valve will effect an emergency application of thetrailer brakes, although no service application thereof will bepossible. I

On the trailer, in the event of failure of either of lines 'I5 or 11,both trailer reservoir I3 and tractor reservoir 52 would drain toatmosphere on service operation of the brake valve, no power brakingbeing posible on the trailer, but power braking being had in normalmanner on the tractor due to the disposition of check valve 55.

Referring now particularly to Fig. 3 of the drawings, it will beseen-that a modified system has been provided in which a compressor Isupplies fluid under pressure, such as compressed air, to threereservoirs IOI, I02 and I03 through pipes I04, I05 and I05 containingone-way check valves I01, I08 and I09 respectively. A brake valve I I0,of usual design, is provided, and the same is constantly supplied withfluid under pressure from reservoir I02 through pipe III. Relay valvesH2 and H3 are provided, and the chambers 20I of such valves areconnected by pipes Ill and H5 respectively, to the brake valve H0, andare normally connected to atmosphere through the exhaust port in saidbrake valve.

The chamber 202 of relay valve H2 is connected by piping IIS and III, tothe tractor front brake chambers H0 and the tractor rear brake chambersIIS, and chamber. 203 of the relay valve is connected by pipe I20 toreservoir IOI. Chamber 203 of relay valve H3 is connected by pipe I2I toreservoir I03, and chamber 202 of this relay valve is connected by pipeI 22 to the trailer service pipe applying all tractor brakes.

' I 23 which is connected to chamber 250 of trailer reiayemergency valveI25. Tractor reservoir I03 is connected by pipe I26 to trailer emergencypipe I2'I, which is connected to chamber 25I of the relay-emergencyvalve I25. Trailer reservoir 5 I24 is connected by pipe I28 to chamber252 of' the relay-emergency valve and trailer brake chambers I29 areconnected by pipes I30 to chamber 253 of the relay-emergency valve. Agovernor unit I3I is provided for controlling the action of compressorI00 and such governor unit is connected by pipe I32 to reservoir IOI andby pipe I33 to the compressor.

In operation of the above-described system, compressor I00 suppliesfluid under pressure, such as compressed air, to'reservoirs IOI, I02 andI03, the disposition of the three check valves being such that eachreservoir is isolated from the other reservoirs, and no back-flow ispermitted to the, I compressor. Fluid under pressure from reservoir I02is supplied constantly to brake valve I I0 and on operation of suchbrake valve, fluid underpressure will flow to the chambers 20I of relayvalves H2 and H3, depressing the diaphragms 204 therein, closing theexhaust ports 205,-and connecting the chambers 202 and 203. On suchoperation of relay valve II2, reservoir IOI will supply fluid underpressure to front brake chambers ll8 through pipe I20, chambers 203 and202 of relay valve I I2, and pipes H5, and to rear brake chambers II9through pipe" I20, chambers 203 and 202 of relay valve H2, and pipesIII, thereby On the above de-- scribed operation of relay valve II3,fluid under pressure from reservoir I03 will flow to chamber 35 250 oftrailer relay-emergency valve I25, through pipe I2I, chambers 203 and202 of relay valve I I3 and pipes I22 and I23, thereby depressing thediaphragm 254, opening valve 255 and allowing flu'd under pressure fromtrailer reservoir I24 40 to flow to trailer brake chambers I 20 through'pipe I28, chamber 252 of the relay-emergency to be immediatelyconnected to trailer brake I I chambers I23, thereby causing anapplication of the trailer brakes. It will be seen therefore that falureof any of the pipes listed above will re-' sult in an automatic,emergency application of the trailer brakes.

In the event of failure of either of lines I I4 and I I5, on operationof brake valve I I0, reservoir I02 will drain to atmosphere and neitherof the relay valves will be operated. Consequently no braking may be-hadon either the tractor or trailer; The same result will be obtained intheevent of the failure of pipe III except for the fact that reservoirI02 will drain immediately, without any operationof brake valve H0.-

Should any of the lines H6 or I" fail, operain relay valve II2, theother reservoirs will not drain and powe braking may be had on thetrailer.

In case of failure of either of lines I22 or I23, on operation of relayvalve H3, in making a service application, reservoir I03 will drain toatmosphere through pipe I2I, chambers 203 and 202 of relay valve H3, andthrough the broken pipe. Draining of reservoir I03 will result in adecrease in pressure in chamber 25I of the relayemergency valve I25, andconsequently trailer reservoir I24 will be connected to trailer brakechambers I29 through pipe I28, chamber 252 of the relay-emergency valve,between the annular ridge 259 and the diaphragm 258, to chamber 253, andthrough pipes I30. The failure of either of the pipes noted above willnot affect the operation of the tractor brakes and therefore a normalamount of braking will result on the tractor and trailer vehicles,although the trailer braking will be in the nature of an emergencyoperation.

It should be noted that in the event of failure of any of pipes I04,I05, I06, I20, III, I26, I2I or I32, pressure cannot be built up in anyof the reservoirs until the broken line is repaired or reservoirconnected to the broken line is shut off from the other reservoirs, asall fluid discharged from the compressor will immediately go toatmosphere through the broken line.

Referring now particularly to Fig. 4 of the drawings, the samedisclosing a modified system according to the present invention, it willbe observed that a compressor I50 supplies fluid under pressure to threereservoirs I5I, I52 and I53 through pipes I54, I55, and I56, such pipesincluding one-way check valves I51, I58 and I59 which allow compressedfluid to flow from the compressor to the reservoirs but prevent flowfrom any one of the reservoirs to the compressor or to any otherreservoir. Reservoir I52 is connected by pipe I60 to brake valve I6I andconstantly supplies fluid under pressure thereto. Relay valves I62 andI63 are provided, pipe I64 connecting chamber 20I of relay valve I62 tothe brake valve, and pipes I65 and I66 connecting relay valve I63 to thebrake valve. Pipe I 66 isconnected to pipes I61 leading to the tractorrear brake chambers I68. Chamber 202 of relay valve I62 is connected tothe tractor front brake chambers I69 by pipes I10, and chamber 203 ofrelay valve I62 is connected by pipe I1I to reservoir I5I. Reservoir I5Iis also connected by pipe I12 to trailer emergency line I 13, which isconnected to chamber" 25I of the trailer relay-emergency valve I14, suchchamber being therefore, subject at all times to the pressure ofreservoir I 5I and such pressure in chamber 25I therefore maintainingthe central portion of diaphragm 258 raised and valve 251 in openposition. Chamber 203 of relay valve I63 is connected by pipe I15 toreservoir I 53, and chamber 202 is connected to pipe I 16 which isconnected to the trailer service line I11,the same being connected tochamber 250 of trailer relay-emergency valve I 14. Trailer reservoir I18is connected by pipe I19 to chamber 252 of the relay-emergency valve I14and pressure from said reservoir constantly acts on the upper side ofdiaphragm 258, maintaining the marginal portion thereof in sealedengagement with the valve casing. Trailer brake chambers I80 areconnected by pipes I8I to chamber 253 of the relay emergency valve I14and are normally connected to atmosphere through said valve. A governorunit I82 is provided for regulating the action of the compressor, suchunloader being connected to reservoir I5I through I50 through pipe onoperation of said brake valve to effect a normal 10 service application,such compressed fluid is supplied by the brake valve to chambers 20I ofrelay valves I62 and I63, through pipe I64 and pipes I66 and I65respectively, depressing the diaphragms therein, shutting ofi theexhaust, open- 15 ings 205, and connecting chambers 202 and 203.Compressed fluid from reservoir I52 also flows directly to the tractorrear brake chambers I68 through pipe I60, brake valve I6I, and pipes I66and I61, thereby causing a service application of 20 such brakes. Theabove-described operation of relay valve I62 causes compressed fluid inreservoir I5I 'to flow to the tractor front brake chambers I69, causinga service application thereof.

The described operation of relay valve I63 causes 25 I compressed fluidin tractor reservoir I53 to flow to the chamber 250 of trailerrelay-emergency valve I14through pipe I15, chambers 203 and 202 of relayvalve I 63, pipe I 16, and trailer service line I11, thereby depressingdiaphragm 254 of the 30 relay-emergency valve I14 and allowingcompressed fluid in trailer reservoir I18 to flow to the trailer brakechambers I80 through pipe I19,

chamber 252 of the relay-emergency valve I14,

past opened valve 255, chamber 256, past opened 35 valve 251, chamber253, and pipes I8I, efiecting a service application of the trailerbrakes. The above describes a normal service brake application.

In order to describe an emergency operation it 40 is necessary to assumethat certain pipes break or otherwise fail. If it be assumed that any ofpipes I1I, I12, I13, or I83 break or otherwise fail, reservoir I5I wouldimmediately drain to atmosphere, the resulting drop in pressure in 45chamber 25I of relay-emergency valve I14 causing the center portion ofdiaphragm 258 to be depressed and valve 251 to close, thereby causing'fluid under pressure in trailer reservoir I 18 to flow to trailer brakechambers I80 through pipe 50 I19, chamber 252 of the relay-emergencyvalve I14, past the annular ridge 259, chamber 253, and pipes .I8I,thereby applying the trailer, brakes. It should be noted that suchoperation is immediate and automatic and is not dependent 55 suchtrailer reservoir presure to flow to trailer brake chambers I80, therebyeffecting a service operation of the trailer brakes. It will be notedthat in the event of failure of the pipes noted, the tractor frontbrakes I69 will not be operated but, due to the interposition of theone-way check valves and the relay valve I 62, the operation of thetractor rear brakes I68 will not be affected.

I as

, Y chamber 252,

v the ruptured, lines,

- drain to atmosphere immediately and no fluid under pressure will beavailable, when brake valve I6I is operated, to effect the -operation ofrelay valves I62. and I63 or to operate the tractor rear brake chambersI68. Consequently no power braking will be available in the' event ofthe above-noted failure.

Assuming failure of any of pipes I64, I65, I66 or I61, on operation ofbrake valve I6I to effect a service application, reservoir I52 willdrain to atmosphere through pipe I66, brake valve I6I and the brokenline. In this condition, as in the preceding situation, no compressedfluid will be available to initiate'brakin'g and hence no power brakingwill be available on either tractor ortrailer.

In the event of failure of any of pipes I15, I16, or I11, on operationof brake valve'I6I and relay valve I63, no compressed fluid will betransmitted to chamber 256 of relay-emergency valve I14 and consequentlythere will be no service braking on the trailer. Due to the fact that noreduction of pressure in reservoir II has occurreddue to there will beno emergency trailer application. will occur, however, on the tractorvehicle due to the interposition of the check valves and relay valves.

' In the event of failure of pipes I6I, trailer reservoir I18 will drainto atmosphere when a normal service application is attempted, throughpipe I19, past opened valve 255, chamber 256, past opened valve 251,chamber 253, and through the broken line I8 I chamber 252 will causetractor reservoir I5I to drain to atmosphere through pipes I12 and I13,chamber 25I, past the edge of diaphragm 256, past opened valve 255,chamber 256, past opened valve 251, chamber 253 and through the rupturedline, thereby preventing operation of the tractor front brakes, but notpreventingnormal operation of the tractor rear brakes fed from reservoirI52.

In case of failure of pipe I16, trailer reservoir I13 will immediatelydrain to atmosphere and the consequent reduction in pressure in chamber25I of the relay-emergencyvalve will cause tractor reservoir I5I todrain'to'atmosphere as outlined 4 above, thereby preventing operation ofthe tractor front brakes but not the tractor rear brakes.

Referring now particularly to Fig. 5' of the drawings, the samedisclosing a further modified system, a compressor 366 supplies fluidunder pressure to reservoirs 36I, 362 and 363 through pipe 364 andbranch pipes leading therefrom to each of the reservoirs, each of saidbranch pipes including a one-way check valve, respectively numbered 365,366 and 361, whereby compressed fluid may flow to each of the reservoirsbut may not flow from any one of the reservoirs to either 3" toreservoir 36I.

' 3 is connected by pipes 3I6 to tractor rear the compressor or anyother reservoir. A brake valve 363 is provided and the same isconstantly supplied with compressed fluid from. reservoir 362 throughpipe 366. Relay valves 3I6 and 3| I- are provided and the chamber 26I ofeach of said relay valves is connected to the brake valve 366, relayvalve 3I6 being connected by pipe' 3I2 and relay valve.3II by pipes 3I3and 3I4. Chamber 262 of relay valve 3I6 is connectedby pipes 3I5 totractor front brake chambers 3I6, and chamber 263 of relay valve 3I6 isconnected by pipe Chamber 262 of relay valve brake chambers 3I3, andchamber 263 of relay 'on p Normal service application l as compressedair, to reservoirs The reduction of pressure in valve 3 is connected bypipe 326 to reservoir 363. A third relay valve 32I is provided, andchamber 26I thereof is connected by pipes" 3I3 and 322 to the brakevalve 366. Chamber 263 of relay valve 32I is connected. by pipes 3" and5 323 to chamber 263 of relay valve 3I6. Chamber 262 of relay valve 32Iis connected to the trailer service line 324 by pipe'325, the trailerservice line 324 leading to chamber 256 of trailer relay-emergency val e326. Reservoir 36I is connected to the trailer emergency line 321 by thetrailer emergency line leading to chamber 25I of the relay emergencyvalve 326 and pressure from reservoir 36I thereby normally maintainingdiaphragm 258 raised and 15 valve 251 in open position. Trailerreservoir 323 is connected by pipe 336 to chamber 252 ofrelayeinergencyvalve 326, and pressure therefrom is normally exertedagainst the upper side of diaphragm 256. Trailer brake chambers I areconnected by pipes 332 to chamber 253 of relayemergency valve 326. Agovernor'unit 333 is pro.- v vided for controlling the operation ofcompressor 366, such governor unit being connected by pipe 334 tocompressor 366 and by pipe 335 to pipe 323 thereby connecting toreservoir 36I. -A pressure gauge 336 is provided and is connected bypipes 331 and 323 to reservoir 36I.

In the operation of the above-described system, compressor 366 suppliesfluid under pressure, such 36I, 362 and 363, the disposition of thecheck valves 365, 366 and 361 permitting flow to said reservoirs, butnot in the opposite direction. Reservoir 362 constantly suppliescompressed fluid to brake-valve 366, and on operation of said brakevalve, fluid under pressure from reservoir 362 will flow to the chambers26I of relay valves 3I6, 3 II and 32I, depressing the diaphragmstherein, closing exhaust ports 265, and connecting chambers 262 and 263.Such operation ofrelay valve 3I6 will cause compressed fluid fromreservoir 36 I to flow to tractor front brake chambers 3 I6 th'roughpipe 3", chambers 263 and 262 of relayvalve 3I6, and

, plpes'3l5, thereby effecting a normal -.or service 5 application. Thedescribed operation of relay valve 3" will cause fluid under pressurefrom reservoir 363 to flow to tractor rear brake cham-'" bers 3I3through pipe 326, chambers 263 and 262 of relay valve 3, and pipes 3I3,thereby efi'ect- 5o ing a service application of the rear brakes. Thedescribed operation of relay valve 32I will eifectv the connection ofreservoir 361 to chamber 256 of trailer relay-emergency valve 326through pipe 323, chambers 263 and 262 of relay valve 32Iand pipes 325and 324, thereby depressing diaphragm 254 and opening valve 255, therebyconnecting trailer reservoir 326 to trailer brake chambers 33Ithroughpipe 33.6,chamber 252 of relay-emergency valve 326, past openedvalve 255; chamber'256, past opened valve 251, chamber 253, and pipes332, thereby effecting a service application of the trailer brakes. Theabove describes a normal service operation of the I tractor and trailerbrakingsystems.

An emergency application occurs on the breaking of any of certainpipes'of the system. In the event of the failure of pipe 363, no powerbreaking will be available on either truck or trailer due to thefactthat no compressed fluid will be available to actuate any of the threerelay valves. In the event of failure-of pipe 326, reservoir 363 willimmediately drain to the atmosphere and the tractor rear brakes cannot,therefore, be operated. Due to the interposition of relayvalves 3 HI and3 normal operation ofthe tractor front brakes and trailer brakes may behad. The same result will be had if pipe 3l8 breaks, in this casereservoir 333 not draining until relay valve 3| I is 5 operated.

' In case of failure of any of pipes 3", 323, 328, 321, 335 or 331,reservoir 3" will drain to atmosphere immediately and no operation ofthe tractor front brakes will therefore be available. The

consequent reduction of pressure in chamber 25l of relay-emergency valve328 due to the draining of reservoir 3! will operate to connect trailerreservoir 323 to trailer brake chambers 33l, through pipe 333, chamber252 of relay-emergency valve 325,, past the annular ridge 259, chamber253, and pipes 332. It should be noted that such operation is entirelyautomatic and does not depend on operation 'of the brake valve. Thedraining of reservoir 3M will also prevent the normal service operationof the trailer brakes due to the fact that compressed fluid cannot besupplied to chamber 258 of relay-emergency valve. The same results willfollow from the failure of any of pipes H5, 325 or 323, except that thedraining of reservoir'llltwill not occur until either of relay valves3lll or 32! are operated, the emergency operation ofthe relay-emergencyvalve 326 taking place at that time instead of immediately.

In the event of failure of any of pipes 3|2, 3l3,

3 or 322, reservoir 382 will drain to atmosphere on operation of brakevalve 388, thereby preventing the operation of any of the relay valves3H, 3H or32 I thereby precluding the operation. of

35 either the tractor or trailer brake systems.

In the event of failure of pipe 338, the trailer reservoir willimmediately drain to atmosphere, and the consequentreduction of pressureon the upper side of diaphragm 258 in relay-emergency 40 valve 326 willcause tractor reservoir 3M to drain to atmosphere through pipe 328, pipe321, chamber 25! of the relay-emergency valve, past the edge ofdiaphragm 258, chamber 252, and through, the broken line to atmosphere.Draining of reservoir 33l will prevent operation of tractor 2 a frontbrake chamber 3I6, the tractor rear brakes being only applied onoperation of brake valve .338. A

Assuming failure. of pipes 332, leading'to the '50 trailer brakechambers, on operation of the relayemergency valve 326 to give a serviceapplication, trailer reservoir 323 will drain to atmosphere through pipe330, chamber 252 of relay-emergency valve 328, past. opened valve 255,chamber 256,

65. past opened valve 251, chamber 253 and through the broken line.Draining of reservoir 329 will cause a consequent reduction in pressureon the upper side of diaphragm 258, resulting in the draining of tractorreservoir 3M to atmosphere through. pipe 328,'pipe 321, chamber 25l ofthe relay-emergency valve, past the edge of diaphragm 258, chamber, 252,past opened valve 255,

chamber 256, past opened valve 251, chamber 253,

and through the broken line. Tractor. front brakes 3l8 cannot thereafterbe applied due to wthedraining of reservoir ill", but the tractor rearbrakes 3l9 may be actuated due to the interposition of the check valvesand relay valves.

It will be seen from the above descriptions that a number of novelbraking systems have been provided which insure 'power braking on atractor-trailer vehicle under almost all adverse operating conditions.While certain arrangements and modifications of the system have beenillustrated and described herein, it is'to be expressly 5 understoodthat the invention is not limited thereto, but may be embodied in othertractor-trailer systems, as will be understood by those skilled in theart. Reference will therefore be had to the appended claims for adefinition of the limits of 10 the invention.

What is claimed is: I

.1. A fluid pressure braking system comprising' a compressor, aplurality of reservoirs connected thereto, tractor braking devices,trailer braking 15 devices," a tractor-carried relay valve forconnecting one of said reservoirs to said trailer braking devices, arelay valve for connecting another of said reservoirs to said tractorbraking devices, independent fluid pressure operated means forgooperating both of said relay valves, and a unitary manually-operablevalve for simultaneously connecting said plurality of reservoirs to saidfluid pressure operated means in order to effect opera- 3 tion of saidrelay valves. 5 2. A fluid pressure braking system comprising tractorfront brakin'g devices, tractor rear braking devices, trailer brakingdevices, control means for said trailer braking devices, a plurality oftractor-carried reservoirs, valve means for con- 3 necting one of saidreservoirs to said tractor front brakes,'valve means for connectinganother of said reservoirs to said control means, and means forconnecting another; of said reservoirs to said first-named valve means,said second-named valve 35 means, and said tractor rear braking devicesfor simultaneously operating the same.

3. A fluid pressure braking system comprising tractor front brakingdevices, tractor rear braking devices, trailer braking devices, controlmeans 40 for said trailer braking devices, a plurality oftractor-carried reservoirs, means for connecting one of said reservoirsto said tractor front brakes,

- means for connecting said reservoir to said control means, means forconnecting another of said 45 reservoirs to said tractor rear brakingdevices, and means for connecting another of said reservoirsto each ofsaid three connecting means.

4. In a fluid pressure tractor-trailer braking system, braking devicesonsaid tractor, braking 5 devices on said trailer, a pressure-operatedrelay valve carried by the trailer for controlling the application offluid pressure to said trailer braking devices, a pressure-operatedrelay valve carried by the tractor for controlling the application offluid pressure to said first named relay valve, a compressor, aplurality of reservoirs, connections between saidcompressor andreservoirs including one-way check valves permitting fiow of fluid fromsaid compressor to said reservoirs only, a pressure- 60 operated relayvalve on the tractor for connecting one of said reservoirs to saidtractor braking devices, connections between said tractor-carried relayvalves 'and said reservoirs including a unitary control valve forsimultaneously supplying 55 said last named relay valves .with fluidpressure to operate the same, and one-way check valves in said lastnamed connections for preventing communication, between said reservoirs.

WILFRED A. EATON. 70

